MDL

NTDEV
1

Hi all.
Tell me please.
When I compose the MDL for NB, what should be the MdlFlags parameter of the MDL structure.
When I watch outgoing packets, the value of MdlFlag changes
4100 - 0001 0000 0000 0100
16412 - 0100 0000 0001 1100
12 - 0000 0000 0000 1100
when i allocate mdl to connect to NB using NdisAllocateMdl, MdlFlag is 12 (MDL_ALLOCATED_FIXID_SIZE | MDL_SOURCE_IS_NONPAGED_POOL)

Do I need to change this value and how?
Where can i find a read about it?
If I will not change the MdlFlags of the newly allocated MDLs, could this be causing network connections to not work properly?

2

How to attach mdl to NB? Is this code is right?

VOID FilterSendNetBufferLists(NDIS_HANDLE FilterModuleContext, PNET_BUFFER_LIST NetBufferLists, NDIS_PORT_NUMBER PortNumber, ULONG SendFlags)
{
NET_BUFFER_LIST_NEXT_NBL(pNBL) = NULL;
PNET_BUFFER_LIST cloneNBL = NdisAllocateCloneNetBufferList(pNBL, NULL, NULL, NDIS_CLONE_FLAGS_USE_ORIGINAL_MDLS);//osr how_to_send_cloned_nbl
NET_BUFFER_LIST_NEXT_NBL(pNBL) = pTemp;
cloneNBL->SourceHandle = pFilter->FilterHandle;
for (int i = 0; i < MaxNetBufferListInfo; i++) NET_BUFFER_LIST_INFO(cloneNBL, i) = NET_BUFFER_LIST_INFO(pNBL, i); // I dont know why

}

NTSTATUS NdisEncryptDeviceIoControl(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
for (all NBs in NBL) {
PUCHAR pBuffer = NdisAllocateMemoryWithTagPriority(pFilter->FilterHandle, IrpSp->Parameters.DeviceIoControl.InputBufferLength - 1, FILTER_ALLOC_TAG, NormalPoolPriority);
RtlCopyMemory(pBuffer, (PUCHAR)Irp->AssociatedIrp.SystemBuffer + 1, IrpSp->Parameters.DeviceIoControl.InputBufferLength - 1);
PMDL pMdl = NdisAllocateMdl(pFilter->FilterHandle, pBuffer, IrpSp->Parameters.DeviceIoControl.InputBufferLength - 1);
pNB->MdlChain = pMdl;
pNB->DataLength = IrpSp->Parameters.DeviceIoControl.InputBufferLength - 1;
pNB->DataOffset = 0;
pNB->CurrentMdl = pMdl;
pNB->CurrentMdlOffset = pMdl->ByteOffset;
}

pNBL->Status = NDIS_STATUS_SUCCESS;
NdisFSendNetBufferLists(pFilter->FilterHandle, pNBL, NDIS_DEFAULT_PORT_NUMBER, 1);

}